A motor and its parameter determination method, apparatus, storage medium, and program product.

Abstract

This invention discloses a method, apparatus, motor, storage medium, and computer program product for determining motor parameters. The method includes: sending a PWM signal to an inverter while the motor is stationary, controlling the six bridge arms of the inverter to conduct in a preset manner, so as to obtain the current PWM carrier cycle by combining the rated current and the three-phase current of the motor; sending a PWM signal to the inverter again in the current PWM carrier cycle, again controlling the six bridge arms of the inverter to conduct in the preset manner, so as to calculate the line current of the motor based on the three-phase current of the motor; and calculating the position angle, quadrature-axis inductance, and direct-axis inductance of the motor based on the line current, as the parameters of the motor to be determined. This scheme, by controlling the six bridge arms of the inverter to conduct in a preset manner, and then calculating the parameters to be identified based on the obtained line current, can improve the accuracy and precision of motor parameter identification.

Description

Technical Field

[0001] This invention belongs to the field of motor technology, specifically relating to a method, apparatus, motor, storage medium, and computer program product for determining motor parameters, and particularly to a method, apparatus, motor, storage medium, and computer program product for identifying parameters of a permanent magnet synchronous motor. Background Technology

[0002] Electric motors (such as permanent magnet synchronous motors) possess numerous advantages, including simple structure, small size, high efficiency, high power density, fast response speed, and high safety, making them widely used in high-performance applications. High-performance motor control methods—vector control, direct torque control, etc.—all rely on the mathematical model of the motor. However, an AC motor is a multivariable, strongly coupled, time-varying nonlinear system. The mathematical model of the motor derived from electromagnetic field theory is a high-order, time-varying mathematical model, and there are certain coupling relationships between the various parameters. To achieve high-performance and precise motor control, accurate motor parameters are essential. However, in current solutions, the accuracy of obtaining motor parameters cannot be guaranteed.

[0003] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0004] The purpose of this invention is to provide a method, device, motor, storage medium, and computer program product for determining motor parameters, in order to solve the problem that the accuracy of motor parameter acquisition cannot be guaranteed in related solutions. This invention achieves the effect of improving the accuracy and precision of motor parameter identification by controlling the six bridge arms of the inverter to conduct in a preset manner and then calculating the parameters to be identified based on the acquired line current.

[0005] This invention provides a method for determining the parameters of a motor, the motor having a drive system and three-phase windings; the drive system of the motor having an inverter, the inverter having a three-phase full-bridge inverter bridge composed of a first switch, a second switch, a third switch, a fourth switch, a fifth switch, and a sixth switch, wherein the first switch and the fourth switch are the upper and lower bridge arm switches of the A-phase bridge arm and are used to supply power to the U-phase winding of the motor's three-phase windings, the third switch and the sixth switch are the upper and lower bridge arm switches of the B-phase bridge arm and are used to supply power to the V-phase winding of the motor's three-phase windings, and the fifth switch and the second switch are the upper and lower bridge arm switches of the C-phase bridge arm and are used to supply power to the W-phase winding of the motor's three-phase windings; the method for determining the parameters of the motor includes: obtaining a pre-set PWM carrier period as an initial PWM carrier period; obtaining the rated current of the motor; and, when the inverter is turned on, obtaining the three-phase full-bridge inverter bridge of the motor. Phase current; when the motor is stationary, a PWM signal is sent to the inverter according to the initial PWM carrier cycle to control the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter to conduct in a preset manner, so as to: update the initial PWM carrier cycle by combining the rated current of the motor and the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle, and obtain the current PWM carrier cycle; according to the current PWM carrier cycle, a PWM signal is sent to the inverter again to control the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter to conduct in a preset manner again, so as to: calculate the line current of the motor based on the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle; calculate the required parameters of the motor based on the line current of the motor.

[0006] In some embodiments, the upper and lower arms of phase A, phase B, and phase C of the inverter are turned on in a preset manner by controlling the upper and lower arm switches of phase A, phase B, and phase C to sequentially operate in a first, second, third, and fourth state. The inverter operates in six different states, including: a first state where the upper arm switch of phase A is on and the lower arm switch is off; a second state where the upper arm switch of phase B is off and the lower arm switch is on; and a third state where the upper arm switch of phase C is off and the lower arm switch is off. The first operating state is as follows: The upper and lower bridge arm switches of phase C are both off; the second operating state is as follows: The upper and lower bridge arm switches of phase A are both off, the upper bridge arm switch of phase B is on and the lower bridge arm switch is off, and the upper bridge arm switch of phase C is off and the lower bridge arm switch is on; the third operating state is as follows: The upper and lower bridge arm switches of phase A are both off, the upper bridge arm switch of phase B is off and the lower bridge arm switch is on, and the upper bridge arm switch of phase C is off and the lower bridge arm switch is on. The first operating state is: the upper bridge arm switch of phase A of the inverter is turned off and the lower bridge arm switch is turned on; both the upper and lower bridge arm switches of phase B are turned off; the upper bridge arm switch of phase C is turned on and the lower bridge arm switch is turned off. The second operating state is: the upper bridge arm switch of phase A of the inverter is turned on and the lower bridge arm switch is turned off; both the upper and lower bridge arm switches of phase B are turned off; the upper bridge arm switch of phase C is turned off and the lower bridge arm switch is turned on.

[0007] In some embodiments, after the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter are turned on in a preset manner, the inverter can be in any one of the following operating states: a first operating state, a second operating state, a third operating state, a fourth operating state, a fifth operating state, and a sixth operating state. A PWM signal is sent to the inverter to control the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm to be turned on in a preset manner, so as to: combine the rated current of the motor, And, when controlling the inverter according to the initial PWM carrier cycle, the three-phase current of the motor is obtained, the initial PWM carrier cycle is updated to obtain the current PWM carrier cycle, including: determining the current threshold of the motor according to the rated current of the motor; sending a PWM signal to the inverter to turn on the inverter according to the first operating state, and then adjusting the pulse width of the PWM signal until the maximum value of the three-phase current of the motor is greater than the current threshold of the motor, then stopping the sending of the PWM signal to the inverter, and recording the pulse width of the PWM signal at this time, denoted as the PWM. The first pulse width of the signal; after a delay until the three-phase current of the motor is 0, a PWM signal is sent to the inverter to turn it on according to the second operating state. Then, the pulse width of the PWM signal is adjusted until the maximum value of the three-phase current of the motor is greater than the current threshold of the motor. At this point, the PWM signal is stopped being sent to the inverter, and the pulse width of the PWM signal at this time is recorded as the second pulse width of the PWM signal. This process is repeated sequentially according to the third, fourth, fifth, and sixth operating states. A PWM signal is sent to turn on the inverter, and the third, fourth, fifth, and sixth pulse widths of the PWM signal are obtained sequentially. After a delay until the three-phase current of the motor is 0, the minimum pulse width among the first, second, third, fourth, fifth, and sixth pulse widths of the PWM signal is determined to update the initial PWM carrier period and obtain the current PWM carrier period.

[0008] In some embodiments, after the upper and lower arms of phase A, phase B, and phase C of the inverter are turned on according to a preset method, the inverter can be in any one of the following operating states: a first operating state, a second operating state, a third operating state, a fourth operating state, a fifth operating state, and a sixth operating state. The line current of the motor includes: a first line current, a second line current, a third line current, a fourth line current, a fifth line current, and a sixth line current. A PWM signal is sent to the inverter again to control the upper and lower arms of phase A, phase B, and phase C of the inverter to be turned on again according to the preset method, so as to: calculate the line current of the motor based on the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle, including: sending a PWM signal to the inverter according to the first operating state. A PWM signal is sent to turn on the inverter. After one current PWM carrier cycle, the sending of the PWM signal to the inverter stops, and the line current of the motor is calculated based on the three-phase current of the motor at this time, which is used as the first line current. After a delay of three current PWM carrier cycles, a PWM signal is sent to the inverter to turn on the inverter according to the second operating state. After one current PWM carrier cycle, the sending of the PWM signal to the inverter stops, and the line current of the motor is calculated based on the three-phase current of the motor at this time, which is used as the second line current. In this way, PWM signals are sent to the inverter to turn on the inverter in sequence according to the third, fourth, fifth and sixth operating states, and the third, fourth, fifth and sixth line currents are obtained in sequence to obtain the line current of the motor.

[0009] In some embodiments, the parameters of the motor include the motor's position angle, and the motor's quadrature-axis inductance and direct-axis inductance; the required parameters of the motor are calculated based on the motor's line current, including: calculating the motor's line inductance based on the motor's line current; calculating the motor's shaft inductance based on the motor's line inductance; the motor's shaft inductance includes: the motor's quadrature-axis inductance and direct-axis inductance; calculating the motor's position angle based on the motor's shaft inductance; and using the calculated motor position angle, and the motor's quadrature-axis inductance and direct-axis inductance, as the required parameters of the motor.

[0010] In some embodiments, the line current of the motor includes: a first line current, a second line current, a third line current, a fourth line current, a fifth line current, and a sixth line current; the line inductance of the motor includes: a first line inductance, a second line inductance, and a third line inductance; calculating the line inductance of the motor based on the line current includes: calculating the line inductance of the motor using the following formula based on the line current:

[0011]

[0012] Among them, L ab L bc L ca The three line inductances of the motor are, in order, the first line inductance, the second line inductance, and the third line inductance, U. dc I is the bus voltage on the input side of the inverter. ab Let L be the first line current. ba For the second line current, I bc For the third line current, I cb For the fourth line current, I ca For the fifth line current, I ac For the sixth line current, R S Let be the stator resistance of the motor, ΔT be the time delay, k1 be the first calculation coefficient, and k2 be the second calculation coefficient.

[0013] And / or, based on the line inductance of the motor, the shaft inductance of the motor is calculated, and based on the shaft inductance of the motor, the position angle of the motor is calculated, including: based on the line inductance of the motor, the shaft inductance of the motor and the position angle of the motor are calculated using the following formula:

[0014]

[0015] Among them, L ab L bc L ca The three line inductances of the motor are, in order, the first line inductance, the second line inductance, and the third line inductance, L. d L is the quadrature-axis inductance of the motor. q Let θ be the direct-axis inductance of the motor. e Let be the position angle of the motor, and k3 be the third calculation coefficient.

[0016] In conjunction with the above method, another aspect of the present invention provides a parameter determination device for a motor, the motor having a drive system and three-phase windings; the drive system of the motor having an inverter, the inverter having a three-phase full-bridge inverter bridge composed of a first switch, a second switch, a third switch, a fourth switch, a fifth switch, and a sixth switch, wherein the first switch and the fourth switch are the upper and lower bridge arm switches of the A-phase bridge arm, and are used to supply power to the U-phase winding in the three-phase windings of the motor, and the third switch and the sixth switch are the B-phase bridge arm switches. The upper and lower bridge arm switches of the phase bridge arm are used to supply power to the V-phase winding of the three-phase winding of the motor; the fifth and second switches are the upper and lower bridge arm switches of the C-phase bridge arm and are used to supply power to the W-phase winding of the three-phase winding of the motor; the parameter determination device for the motor includes: an acquisition unit configured to acquire a preset PWM carrier period as an initial PWM carrier period; acquire the rated current of the motor; and, when the inverter is turned on, acquire the three-phase current of the motor; control The control unit is configured to send a PWM signal to the inverter according to the initial PWM carrier cycle when the motor is stationary, controlling the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter to conduct in a preset manner, so as to update the initial PWM carrier cycle by combining the rated current of the motor and the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle, and obtain the current PWM carrier cycle; the control unit is configured to send a PWM signal to the inverter according to the initial PWM carrier cycle when the motor is stationary, and control the upper and lower arms of the A-phase bridge arm, the B-phase bridge arm, and the C-phase bridge arm of the inverter to conduct in a preset manner, so as to obtain the current PWM carrier cycle by combining the rated current of the motor and the three-phase current of the motor obtained when the inverter is controlled according to the initial ... controlling the upper and lower arms of the A-phase bridge arm, the B-phase bridge arm, and the C-phase bridge arm to conduct in a preset manner, so as to obtain the current PWM carrier cycle when the initial PWM carrier cycle is updated according to the rated current of the motor and the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle. The control unit is also configured to send a PWM signal to the inverter again according to the current PWM carrier cycle, and control the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter to conduct in a preset manner, so as to calculate the line current of the motor based on the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle; the control unit is also configured to calculate the required parameters of the motor based on the line current of the motor.

[0017] In some embodiments, the upper and lower arms of phase A, phase B, and phase C of the inverter are turned on in a preset manner by controlling the upper and lower arm switches of phase A, phase B, and phase C to sequentially operate in a first, second, third, and fourth state. The inverter operates in six different states, including: a first state where the upper arm switch of phase A is on and the lower arm switch is off; a second state where the upper arm switch of phase B is off and the lower arm switch is on; and a third state where the upper arm switch of phase C is off and the lower arm switch is off. The first operating state is as follows: The upper and lower bridge arm switches of phase C are both off; the second operating state is as follows: The upper and lower bridge arm switches of phase A are both off, the upper bridge arm switch of phase B is on and the lower bridge arm switch is off, and the upper bridge arm switch of phase C is off and the lower bridge arm switch is on; the third operating state is as follows: The upper and lower bridge arm switches of phase A are both off, the upper bridge arm switch of phase B is off and the lower bridge arm switch is on, and the upper bridge arm switch of phase C is off and the lower bridge arm switch is on. The first operating state is: the upper bridge arm switch of phase A of the inverter is turned off and the lower bridge arm switch is turned on; both the upper and lower bridge arm switches of phase B are turned off; the upper bridge arm switch of phase C is turned on and the lower bridge arm switch is turned off. The second operating state is: the upper bridge arm switch of phase A of the inverter is turned on and the lower bridge arm switch is turned off; both the upper and lower bridge arm switches of phase B are turned off; the upper bridge arm switch of phase C is turned off and the lower bridge arm switch is turned on.

[0018] In some embodiments, after the upper and lower arms of phase A, phase B, and phase C of the inverter are turned on according to a preset method, the inverter can be in any one of the following operating states: a first operating state, a second operating state, a third operating state, a fourth operating state, a fifth operating state, and a sixth operating state. The control unit sends a PWM signal to the inverter to control the upper and lower arms of phase A, phase B, and phase C of the inverter to be turned on according to the preset method, so as to: combine with the motor's... The rated current and the three-phase current of the motor obtained when controlling the inverter according to the initial PWM carrier cycle are used to update the initial PWM carrier cycle to obtain the current PWM carrier cycle. This includes: determining the current threshold of the motor based on the rated current of the motor; sending a PWM signal to the inverter to turn on the inverter according to the first operating state; then adjusting the pulse width of the PWM signal until the maximum value of the three-phase current of the motor is greater than the current threshold of the motor; stopping the sending of the PWM signal to the inverter; and recording the pulse width of the PWM signal at this time, denoted as the current threshold. The first pulse width of the PWM signal; after a delay until the three-phase current of the motor is 0, a PWM signal is sent to the inverter in the second operating state to turn on the inverter. Then, the pulse width of the PWM signal is adjusted until the maximum value of the three-phase current of the motor is greater than the current threshold of the motor. At this point, the sending of the PWM signal to the inverter stops, and the pulse width of the PWM signal at this time is recorded as the second pulse width of the PWM signal. This process is repeated sequentially in the third, fourth, fifth, and sixth operating states. The inverter sends a PWM signal to turn on the inverter, and sequentially obtains the third pulse width, the fourth pulse width, the fifth pulse width, and the sixth pulse width of the PWM signal; after a delay until the obtained three-phase current of the motor is 0, the minimum pulse width among the first pulse width, the second pulse width, the third pulse width, the fourth pulse width, the fifth pulse width, and the sixth pulse width of the PWM signal is determined to update the initial PWM carrier period and obtain the current PWM carrier period.

[0019] In some embodiments, after the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter are turned on in a preset manner, the inverter can be in any one of the following operating states: a first operating state, a second operating state, a third operating state, a fourth operating state, a fifth operating state, and a sixth operating state; the line current of the motor includes: a first line current, a second line current, a third line current, a fourth line current, a fifth line current, and a sixth line current; the control unit sends a PWM signal to the inverter again, and again controls the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter to be turned on in a preset manner, so as to: calculate the line current of the motor based on the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle, including: according to the first operating state, sending a PWM signal to the inverter again, and controlling the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm to be turned on in a preset manner, so as to: calculate the line current of the motor based on the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle, including: sending a PWM signal to the inverter again, and controlling ... and controlling the upper and lower arms of the C-phase bridge arm, so as to: calculate the line current The inverter sends a PWM signal to turn on the inverter. After one current PWM carrier cycle, the transmission of the PWM signal to the inverter stops, and the line current of the motor is calculated based on the three-phase current of the motor at this time, which is used as the first line current. After a delay of three current PWM carrier cycles, the inverter is sent a PWM signal to turn on the inverter according to the second operating state. After one current PWM carrier cycle, the transmission of the PWM signal to the inverter stops, and the line current of the motor is calculated based on the three-phase current of the motor at this time, which is used as the second line current. In this way, the inverter is sent a PWM signal to turn on the inverter according to the third, fourth, fifth and sixth operating states in sequence, and the third, fourth, fifth and sixth line currents are obtained in sequence to obtain the line current of the motor.

[0020] In some embodiments, the parameters of the motor include the motor's position angle, and the motor's quadrature-axis inductance and direct-axis inductance; the control unit calculates the required parameters of the motor based on the motor's line current, and the calculation of the required parameters of the motor includes: calculating the motor's line inductance based on the motor's line current; calculating the motor's shaft inductance based on the motor's line inductance; the motor's shaft inductance includes: the motor's quadrature-axis inductance and direct-axis inductance; calculating the motor's position angle based on the motor's shaft inductance; and using the calculated motor position angle, and the motor's quadrature-axis inductance and direct-axis inductance as the required parameters of the motor.

[0021] In some embodiments, the line current of the motor includes: a first line current, a second line current, a third line current, a fourth line current, a fifth line current, and a sixth line current; the line inductance of the motor in the control unit includes: a first line inductance, a second line inductance, and a third line inductance; calculating the line inductance of the motor based on the line current includes: calculating the line inductance of the motor using the following formula based on the line current:

[0022]

[0023] Among them, L ab L bc L ca The three line inductances of the motor are, in order, the first line inductance, the second line inductance, and the third line inductance, U. dc I is the bus voltage on the input side of the inverter. ab For the first line current, I ba For the second line current, I bc For the third line current, I cb For the fourth line current, I ca For the fifth line current, I ac For the sixth line current, R S Let be the stator resistance of the motor, ΔT be the time delay, k1 be the first calculation coefficient, and k2 be the second calculation coefficient.

[0024] And / or, the control unit calculates the shaft inductance of the motor based on the line inductance of the motor, and calculates the position angle of the motor based on the shaft inductance of the motor, including: calculating the shaft inductance of the motor and the position angle of the motor using the following formula based on the line inductance of the motor:

[0025]

[0026] Among them, L ab L bc L ca The three line inductances of the motor are, in order, the first line inductance, the second line inductance, and the third line inductance, L. d L is the quadrature-axis inductance of the motor. q Let θ be the direct-axis inductance of the motor. e Let be the position angle of the motor, and k3 be the third calculation coefficient.

[0027] In conjunction with the above-described device, the present invention further provides a motor, comprising: the above-described motor parameter determination device.

[0028] In conjunction with the above method, the present invention further provides a storage medium comprising a stored program, wherein, when the program is executed, the device on which the storage medium is located executes the steps of the above-described method for determining the parameters of a motor.

[0029] In conjunction with the above method, the present invention further provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the above-described method for determining the parameters of a motor.

[0030] Therefore, the solution of this invention, while the motor (such as a permanent magnet synchronous motor) is stationary, enables the six bridge arms of the inverter to conduct in a preset manner, adjusts the pulse width according to the output current, and shuts off the PWM output when the maximum value of the three-phase current exceeds the current limit. The pulse width is recorded to obtain the minimum value among the six pulse widths, thus determining the minimum PWM pulse width T. The minimum value of the minimum PWM pulse width T is used as the pulse width for the next six PWM waves. The inverter is then sequentially controlled to conduct the corresponding two-phase bridge arms according to the six preset conduction methods, and the line current is recorded. The line inductance of the permanent magnet synchronous motor is calculated to obtain the motor's AC and DC axis inductances L. q L d With position angle θ e In order to obtain the parameters to be identified, by controlling the six bridge arms of the inverter to conduct in a preset manner, the parameters to be identified can be calculated based on the obtained line current, thereby improving the identification accuracy and precision of motor parameters.

[0031] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention.

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating an embodiment of the method for determining the parameters of a motor according to the present invention.

[0034] Figure 2 This is a schematic flowchart of an embodiment of the method of the present invention, which updates the initial PWM carrier period by combining the rated current of the motor and the three-phase current of the motor obtained when controlling the inverter according to the initial PWM carrier period.

[0035] Figure 3 This is a schematic flowchart of an embodiment of the method of the present invention for calculating the line current of the motor based on the three-phase current of the motor;

[0036] Figure 4This is a flowchart illustrating an embodiment of the method of the present invention for calculating the required parameters of the motor based on the line current of the motor.

[0037] Figure 5 This is a schematic diagram of an embodiment of the motor parameter determination device of the present invention;

[0038] Figure 6 This is a schematic diagram of a permanent magnet synchronous motor drive system based on a three-phase voltage source inverter.

[0039] Figure 7 A simplified equivalent circuit diagram for a permanent magnet synchronous motor;

[0040] Figure 8 A flowchart illustrating the parameter identification method for permanent magnet synchronous motors.

[0041] Referring to the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0042] 102 - Acquisition unit; 104 - Control unit. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0044] Considering that for motors (such as permanent magnet synchronous motors), if the parameters of the designed motor controller are not properly matched with the parameters of the controlled motor, it will affect the control performance of the entire system. Therefore, it is necessary to identify the motor parameters and obtain the actual motor parameters. The control performance of a motor is highly dependent on the accuracy of its parameters. Several factors can lead to improper matching between the controller and the controlled motor parameters, such as: the motor nameplate being lost or damaged, making it impossible to obtain the design parameters; the motor parameters are mainly provided by the motor manufacturer, but the provided parameters are the design parameters from the motor design stage and may have errors compared to the parameters of the actual manufactured motor; during the actual operation of the motor, the parameters will change due to factors such as temperature, magnetic circuit saturation, and current.

[0045] Parameter identification, a branch of modern control theory, combines theoretical models with experimental data, then analyzes and predicts to obtain precise parameters. With increasing demands on motor control performance, the accuracy and efficiency of parameter identification also need to be improved. In related schemes, parameter identification methods for permanent magnet synchronous motors are mainly divided into two categories: offline identification methods and online identification methods. The basic idea of ​​offline identification is to input specific voltage and current excitation signals to the motor before startup, and then collect the voltage, current, and angle values ​​of the motor at this time through sensors in the driver. Based on the mathematical model of the permanent magnet synchronous motor, the required motor parameters are obtained through fitting or calculation. Online identification methods can obtain motor parameters in real time and adjust the control system in real time based on these parameters to achieve better control performance.

[0046] One method for identifying motor parameters in some solutions involves sequentially controlling the inverter to conduct any two phase arms of the bridge according to a first preset conduction mode and a second preset conduction mode. In the first preset conduction mode, a forward voltage pulse is applied to the windings of the permanent magnet synchronous motor (PMSM), and in the second preset conduction mode, a reverse voltage pulse is applied to the windings. The method acquires the DC bus voltage under the forward voltage pulse, and collects the first and second current values ​​of the corresponding windings on the conducting arms at different times under the forward voltage pulse. The quadrature-axis inductance parameters and direct-axis inductance parameters are calculated based on the DC bus voltage under the forward voltage pulse, the first and second current values, and the current acquisition time interval. However, this method is complex and requires a pulse signal generator, and involves acquiring numerous parameters such as the first, second, and third bus voltages, the first, second, third, fourth, fifth, and sixth line currents, and the current acquisition time interval.

[0047] Some disclosed methods for determining motor parameters involve applying a set pulse voltage to the motor while it is stationary to determine its inductance parameters. This allows for the determination of the inductance-current relationship based on the inductance parameters under different currents. The set pulse voltage has an amplitude greater than or equal to a set amplitude and an duration less than or equal to a set duration. The motor parameters include: inductance parameters; these inductance parameters include: direct-axis inductance and quadrature-axis inductance; the direct-axis inductance includes: direct-axis static inductance and direct-axis dynamic inductance; and the quadrature-axis inductance includes: quadrature-axis static inductance and quadrature-axis dynamic inductance. However, in practice, it is necessary to maintain the rotor position at 0 degrees and 90 degrees respectively. But in actual operation, especially in motors without resolver encoders, maintaining the rotor position at a precise angle is difficult to achieve.

[0048] In other words, errors between the motor parameters and the actual parameters lead to a mismatch between the designed motor controller parameters and the controlled motor parameters, thus affecting the motor controller's control performance. Furthermore, motor parameter identification is divided into offline and online parameter identification, and different identification methods are used for different motor parameters, resulting in varying parameter accuracy. Even with the same offline parameter identification method, the implementation methods differ; not all offline parameter identification methods use the same approach. For example, motor parameters change with operating temperature. The stator resistance and the permeability of the ferromagnetic material have a non-linear relationship with temperature, and the degree of magnetic circuit saturation also affects motor parameters.

[0049] Therefore, the present invention proposes a method for determining motor parameters, specifically a method for identifying parameters of a permanent magnet synchronous motor. When the motor is stationary, the inverter is sequentially controlled to conduct the corresponding two-phase bridge arms according to six preset conduction modes. The pulse width is adjusted according to the output current, and then the parameters to be identified are calculated. This method can improve the identification accuracy and precision of permanent magnet synchronous motor parameters, and ensure the accuracy of motor parameter acquisition.

[0050] According to an embodiment of the present invention, a method for determining the parameters of a motor is provided, such as... Figure 1 The diagram shows a flowchart of an embodiment of the method of the present invention. The motor has a drive system and three-phase windings; the drive system of the motor has an inverter, the inverter has a three-phase full-bridge inverter bridge composed of a first switch, a second switch, a third switch, a fourth switch, a fifth switch and a sixth switch, the first switch and the fourth switch are the upper and lower bridge arm switches of the A-phase bridge arm, and are used to supply power to the U-phase winding of the three-phase windings of the motor, the third switch and the sixth switch are the upper and lower bridge arm switches of the B-phase bridge arm, and are used to supply power to the V-phase winding of the three-phase windings of the motor, the fifth switch and the second switch are the upper and lower bridge arm switches of the C-phase bridge arm, and are used to supply power to the W-phase winding of the three-phase windings of the motor, the first switch is VT1, the second switch is VT2, the third switch is VT3, the fourth switch is VT4, the fifth switch is VT5, and the sixth switch is VT6. Figure 6 This is a schematic diagram of a permanent magnet synchronous motor drive system based on a three-phase voltage source inverter. Figure 6 The permanent magnet synchronous motor drive system based on a three-phase voltage source inverter shown includes: a rectifier, a bus capacitor, and an inverter. The rectifier consists of a full-bridge diode rectifier composed of six diodes, and the voltage across the bus capacitor is the bus voltage U. DCThe inverter is a full-bridge inverter consisting of six switching transistors VT1, VT2, VT3, VT4, VT5 to VT6, each with a freewheeling diode. VT1 and VT4 are the upper and lower transistors of the A-phase bridge arm, VT3 and VT6 are the upper and lower transistors of the B-phase bridge arm, and VT5 and VT2 are the upper and lower transistors of the C-phase bridge arm. The permanent magnet synchronous motor drive system based on a three-phase voltage source inverter, after rectification and inversion of the three-phase AC power, provides three-phase current i to the motor's three-phase windings u, v, and w. A i B and i C .

[0051] In some embodiments, the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter are turned on in a preset manner. This means controlling the upper and lower arm switches of the A-phase bridge arm, the B-phase bridge arm, and the C-phase bridge arm to sequentially put the inverter into a first operating state, a second operating state, a third operating state, a fourth operating state, a fifth operating state, and a sixth operating state.

[0052] The first operating state is as follows: the upper bridge arm switch of phase A of the inverter is turned on and the lower bridge arm switch is turned off; the upper bridge arm switch of phase B is turned off and the lower bridge arm switch is turned on; and the upper and lower bridge arm switches of phase C are both turned off.

[0053] The second operating state is as follows: the upper bridge arm switch of phase A of the inverter is turned off and the lower bridge arm switch is turned on; the upper bridge arm switch of phase B is turned on and the lower bridge arm switch is turned off; and both the upper and lower bridge arm switches of phase C are turned off.

[0054] The third operating state is as follows: the upper and lower bridge arm switches of the A-phase bridge arm of the inverter are both off, the upper bridge arm switch of the B-phase bridge arm is on and the lower bridge arm switch is off, and the upper bridge arm switch of the C-phase bridge arm is off and the lower bridge arm switch is on.

[0055] The fourth operating state is as follows: the upper and lower bridge arm switches of the A-phase bridge arm of the inverter are both off, the upper bridge arm switch of the B-phase bridge arm is off and the lower bridge arm switch is on, and the upper bridge arm switch of the C-phase bridge arm is on and the lower bridge arm switch is off.

[0056] The fifth operating state is as follows: the upper bridge arm switch of the A phase bridge arm of the inverter is turned off and the lower bridge arm switch is turned on; both the upper and lower bridge arm switches of the B phase bridge arm are turned off; and the upper bridge arm switch of the C phase bridge arm is turned on and the lower bridge arm switch is turned off.

[0057] The sixth operating state is as follows: the upper bridge arm switch of the A phase bridge arm of the inverter is turned on and the lower bridge arm switch is turned off; both the upper and lower bridge arm switches of the B phase bridge arm are turned off; and the upper bridge arm switch of the C phase bridge arm is turned off and the lower bridge arm switch is turned on.

[0058] Figure 6 The inverter uses upper and lower tube commutation. In the scheme of this invention, seven working states are defined, namely the first working state, the second working state, the third working state, the fourth working state, the fifth working state, the sixth working state, and the seventh working state.

[0059] The first working state is as follows: the upper tube of phase A is on and the lower tube is off; the upper tube of phase B is off and the lower tube is on; and both the upper and lower tubes of phase C are off. That is, VT1 and VT6 are on, and the rest are off.

[0060] The second operating state: Phase A upper tube is off and lower tube is on, Phase B upper tube is on and lower tube is off, and Phase C both upper and lower tubes are off; that is, VT4 and VT3 are on, and the rest are off.

[0061] The third operating state: both the upper and lower tubes of phase A are off, the upper tube of phase B is on and the lower tube is off, the upper tube of phase C is off and the lower tube is on; that is, VT3 and VT2 are on, and the rest are off.

[0062] The fourth operating state: both the upper and lower tubes of phase A are off, the upper tube of phase B is off and the lower tube is on, the upper tube of phase C is on and the lower tube is off; that is, VT6 and VT5 are on, and the rest are off.

[0063] The fifth operating state: Phase A upper tube is off and lower tube is on; Phase B upper and lower tubes are both off; Phase C upper tube is on and lower tube is off; that is, VT4 and VT5 are on, and the rest are off.

[0064] The sixth operating state: Phase A upper tube is on and lower tube is off; Phase B upper and lower tubes are both off; Phase C upper tube is off and lower tube is on; that is, VT1 and VT2 are on, and the rest are off.

[0065] The seventh operating state: all three power devices (A, B, and C) are turned off.

[0066] In the present invention, when the motor is stationary, the inverter is sequentially controlled to conduct the corresponding two-phase bridge arms according to six preset conduction modes. Then, the pulse width is adjusted according to the output current, and the line current of the motor is obtained. Then, the line inductance of the permanent magnet synchronous motor is calculated to obtain the parameters to be identified. This can improve the identification accuracy and precision of the permanent magnet synchronous motor parameters and ensure the accuracy of the motor parameter acquisition.

[0067] In the solution of the present invention, such as Figure 1As shown, the method for determining the parameters of the motor includes steps S110 to S140.

[0068] In step S110, a pre-set PWM carrier period is obtained as the initial PWM carrier period; the rated current of the motor is obtained, such as the rated current I of the permanent magnet synchronous motor. e_motor ; and, when the inverter is turned on, to obtain the three-phase currents (such as currents Ia, Ib, Ic) of the motor.

[0069] In step S120, with the motor stationary, the motor controller sends a drive signal to the motor's drive system, i.e., a PWM signal to the inverter, according to the initial PWM carrier cycle. This controls the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter to conduct in a preset manner. This is done by combining the motor's rated current and the three-phase current of the motor obtained while controlling the inverter according to the initial PWM carrier cycle, updating the initial PWM carrier cycle to obtain the current PWM carrier cycle. Specifically, during the process of controlling the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter to conduct in a preset manner, the three-phase current of the motor is acquired, and the pulse width of the PWM signal is recorded. Then, based on the three-phase current of the motor and the pulse width of the PWM signal, the initial PWM carrier cycle is updated to obtain the current PWM carrier cycle.

[0070] In some implementations, after the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter are turned on in a preset manner, the inverter can be in any one of the first, second, third, fourth, fifth, and sixth operating states. In step S120, a PWM signal is sent to the inverter to control the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm to be turned on in a preset manner. This is to update the initial PWM carrier cycle by combining the rated current of the motor and the three-phase current of the motor obtained when controlling the inverter according to the initial PWM carrier cycle, to obtain the current PWM carrier cycle. For the specific process of obtaining the current PWM carrier cycle, please refer to the following exemplary description.

[0071] The following is combined with Figure 2The schematic diagram shown is a flowchart of an embodiment of the method of the present invention, which combines the rated current of the motor and the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle to update the initial PWM carrier cycle. It further illustrates the specific process of updating the initial PWM carrier cycle in step S120 by combining the rated current of the motor and the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle, including steps S210 to S250.

[0072] Step S210: Determine the current threshold of the motor based on its rated current. Specifically, determine the rated current I of the motor. e_motor The set coefficient multiple is determined as the current threshold I of the motor. threshold Set the coefficient, for example, 0.8.

[0073] Step S220: Send a PWM signal to the inverter to turn on the inverter according to the first working state, and then adjust the pulse width of the PWM signal until the maximum value of the three-phase current of the motor is greater than the current threshold of the motor. Stop sending the PWM signal to the inverter and record the pulse width of the PWM signal at this time, which is recorded as the first pulse width of the PWM signal.

[0074] Step S230: After a delay until the three-phase current of the motor is 0, a PWM signal is sent to the inverter to turn on the inverter according to the second working state. Then, the pulse width of the PWM signal is adjusted until the maximum value of the three-phase current of the motor is greater than the current threshold of the motor. Then, the PWM signal is stopped from being sent to the inverter, and the pulse width of the PWM signal at this time is recorded as the second pulse width of the PWM signal.

[0075] Step S240: PWM signals are sequentially sent to the inverter in the third, fourth, fifth, and sixth operating states to turn on the inverter, and the third, fourth, fifth, and sixth pulse widths of the PWM signals are obtained sequentially. Specifically, the first pulse width of the PWM signal is as shown in pulse width T1, the second pulse width is as shown in pulse width T2, the third pulse width is as shown in pulse width T3, the fourth pulse width is as shown in pulse width T4, the fifth pulse width is as shown in pulse width T5, and the sixth pulse width is as shown in pulse width T6.

[0076] Step S250: After a delay until the obtained three-phase current of the motor is 0, determine the minimum pulse width among the first pulse width, the second pulse width, the third pulse width, the fourth pulse width, the fifth pulse width, and the sixth pulse width of the PWM signal, so as to update the initial PWM carrier period and obtain the current PWM carrier period.

[0077] Figure 7 A simplified equivalent circuit diagram for a permanent magnet synchronous motor. (Example) Figure 7 As shown, the simplified equivalent circuit of the permanent magnet synchronous motor includes: a power supply, a switch S, a diode D, a resistor R, and an inductor Lbc. The power supply voltage is v_dc. The positive terminal of the power supply is connected to the negative terminal of the power supply via the switch S, resistor R, and inductor Lbc; the negative terminal of the power supply is grounded to GND. The anode of diode D is connected to the common terminal between the switch S and the resistor R; the cathode of diode D is grounded to GND. The resistance of resistor R is R = 2Rs, where Rs is the resistance of the motor stator.

[0078] like Figure 6 As shown, disconnect phase A of the motor and connect phases B and C to the positive and negative terminals of the DC power supply, respectively. Fix the motor rotor. At this point, the system simplifies to an RL circuit, i.e. Figure 7 As shown. Where the power supply voltage v_dc is the bus voltage of the motor controller, the resistance R is twice the stator resistance Rs of the motor, and the inductance Lbc is the stator line inductance. When switch S is closed, the voltage u and current i in the RL circuit satisfy:

[0079]

[0080] Among them, L line This is the inductance value of the stator line inductance.

[0081] Because the stator resistance of a high-power motor is relatively small, R*i can be ignored when the current is small, and the above formula can be simplified to:

[0082]

[0083] Therefore, we can conclude that:

[0084] L line =∫udt / i (3)

[0085] That is, inductance L line It equals the integral of voltage u divided by inductance L line When the input voltage U is constant, the current i in the equation can be simplified to:

[0086] L line =U*t / i (4).

[0087] At this time, the inductance L line The current i and voltage U in the RL are linearly related, and this linear relationship only holds true when the current i is very small, that is, in the initial stage of the RL inertial response.

[0088] Where R is the resistance value in the simplified equivalent circuit of the motor, which is twice the stator resistance Rs of the motor; u is the total load voltage in the equivalent circuit; i is the current flowing through the equivalent circuit; L line It is a line inductance, that is Figure 7 The L shown bc t represents the initial stage of the RL inertial response.

[0089] Figure 8 This is a flowchart illustrating the parameter identification method for permanent magnet synchronous motors. Figure 8 As shown, the specific implementation logic of the permanent magnet synchronous motor parameter identification method includes:

[0090] Step 1: Initialize all parameter variables (e.g., operating status, PWM pulse width, delay time, etc.), set the PWM carrier period, and determine the period based on the rated current I of the permanent magnet synchronous motor. e_motor Calculate the current threshold I threshold Then proceed to step 2. Specifically, the carrier frequency can be selected based on the inverter's voltage level. For example, if the inverter's voltage level is DC 540V, the carrier frequency is selected as 4kHz. The PWM carrier period can be determined based on the carrier frequency. The rated current I of the permanent magnet synchronous motor is also considered. e_motor Calculate the current threshold I threshold The method is as follows:

[0091] I threshold =0.8*I e_motor (5).

[0092] Step 2: Enable PWM output and sample the three-phase current. Turn on the inverter in the first operating state (A+B-) and perform pulse width detection and adjustment. For example, the pulse width detection yields a value, which can be added to or subtracted from the three-phase current. Different pulse widths correspond to different three-phase current values. When the maximum value of the three-phase current exceeds the set current threshold I... threshold When the PWM output is turned off, the pulse width T1 at this time is recorded, and then step 3 is executed. Among them, the first working state (A+B-) means that the upper tube of phase A is on and the lower tube is off, the upper tube of phase B is off and the lower tube is on, and both the upper and lower tubes of phase C are off.

[0093] Step 3: Sample the three-phase current, delay for a period of time (until the current returns to 0), and turn on the inverter according to the second operating state (A-B+). Perform pulse width detection and adjustment. When the maximum value of the three-phase current is greater than the set current threshold, turn off the PWM output and record the pulse width T2 at this time. Then execute step 4. The two operating states (A-B+) are: A-phase upper transistor off and lower transistor on, B-phase upper transistor on and lower transistor off, and C-phase both upper and lower transistors off.

[0094] Step 4: Sample the three-phase current, delay for a period of time (until the current returns to 0), and turn on the inverter according to the third operating state (B+C-). Perform pulse width detection and adjustment. When the maximum value of the three-phase current is greater than the set current threshold, turn off the PWM output and record the pulse width T3 at this time. Then execute step 5. The third operating state (B+C-) means that the upper and lower transistors of phase A are both off, the upper transistor of phase B is on and the lower transistor is off, and the upper transistor of phase C is off and the lower transistor is on.

[0095] Step 5: Sample the three-phase current, delay for a period of time (until the current returns to 0), and turn on the inverter according to the fourth operating state (B-C+). Perform pulse width detection and adjustment. When the maximum value of the three-phase current is greater than the set current threshold, turn off the PWM output and record the pulse width T4 at this time. Then execute step 6. The fourth operating state (B-C+) means that both the upper and lower transistors of phase A are off, the upper transistor of phase B is off and the lower transistor is on, and the upper transistor of phase C is on and the lower transistor is off.

[0096] Step 6: Sample the three-phase current, delay for a period of time (until the current returns to 0), and turn on the inverter according to the fifth operating state (C+A-). Perform pulse width detection and adjustment. When the maximum value of the three-phase current is greater than the set current threshold, turn off the PWM output and record the pulse width T5 at this time. Then execute step 7. The fifth operating state (C+A-) means that the upper transistor of phase A is off and the lower transistor is on, both the upper and lower transistors of phase B are off, and the upper transistor of phase C is on and the lower transistor is off.

[0097] Step 7: Sample the three-phase current, delay for a period of time (until the current returns to 0), and turn on the inverter according to the sixth operating state (C-A+). Perform pulse width detection and adjustment. When the maximum value of the three-phase current is greater than the set current threshold, turn off the PWM output and record the pulse width T6 at this time. Then execute step 8. The sixth operating state (C-A+) means that the upper transistor of phase A is on and the lower transistor is off, both the upper and lower transistors of phase B are off, and the upper transistor of phase C is off and the lower transistor is on.

[0098] Step 8: After a delay until the current returns to 0, select the smallest pulse width among the six pulse widths as the pulse width T of the PWM wave, i.e., T = min(T1, T2, T3, T4, T5, T6); set T as the period of the PWM carrier wave, and then execute step 9.

[0099] From the Figure 7 As described, in the simplified equivalent circuit of the motor, when the current is small, especially when the input voltage is constant, the inductor current and voltage exhibit a linear relationship. When the voltage pulse width is small, the current changes almost linearly; when the current is turned off, the current decreases slowly. Steps 2 to 7 respectively follow the preset conduction states, causing the six bridge arms of the inverter to conduct in a preset manner, achieving the desired effect. Figure 7 The simplified RL circuit described in the system is used to determine the minimum pulse width T of the PWM wave. Because the presence of stray inductance, parasitic inductance, stray capacitance, and parasitic capacitance in the entire system can cause inconsistencies in the time it takes for the maximum current in the three phases to reach the set threshold current, i.e., inconsistent PWM wave pulse width times, steps 2 to 7 are used to eliminate the influence of stray inductance, parasitic inductance, stray capacitance, and parasitic capacitance on the line inductance. The minimum pulse width T is the required pulse width. The delay in each step is to allow the current in the circuit to return to zero, meaning that only a single current generated by a single wave exists in the circuit each time.

[0100] In the present invention, when the motor is stationary, the inverter is sequentially controlled to conduct the corresponding two-phase bridge arms according to six preset conduction modes. The pulse width is adjusted according to the output current. When the maximum value of the three-phase current is greater than the current limit, the PWM output is turned off, and the pulse width is recorded to obtain the minimum value among the six pulse widths. This minimum pulse width is used as the pulse width for the next six PWM waves, thereby obtaining the line current of the motor. The line inductance of the permanent magnet synchronous motor is calculated to obtain the parameters to be identified. This can improve the identification accuracy and precision of the permanent magnet synchronous motor parameters, and ensure the accuracy of motor parameter acquisition.

[0101] At step S130, according to the current PWM carrier cycle, the motor controller is again controlled to send a drive signal to the motor drive system, that is, to send a PWM signal to the inverter again. The upper and lower bridge arms of phase A, phase B, and phase C of the inverter are again controlled to conduct in a preset manner, so as to calculate the line current of the motor based on the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle.

[0102] In some embodiments, after the upper and lower arms of phase A, phase B, and phase C of the inverter are turned on according to a preset method, the inverter can be in any one of the following operating states: a first operating state, a second operating state, a third operating state, a fourth operating state, a fifth operating state, and a sixth operating state. The line current of the motor includes: a first line current, a second line current, a third line current, a fourth line current, a fifth line current, and a sixth line current, wherein the first line current is such that line current I... ab The second line current is like the line current I. ba The third line current is such as line current I. bc The fourth line current is such as line current I. cb The fifth line current is like the line current I. ca The sixth line current is like the line current I. ac In step S130, a PWM signal is sent to the inverter again, and the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter are controlled to conduct in a preset manner. The specific process of calculating the line current of the motor based on the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle is described in the following exemplary description.

[0103] The following is combined with Figure 3 The flowchart shown is a schematic diagram of an embodiment of the method of the present invention in which the line current of the motor is calculated based on the three-phase current of the motor. The specific process of calculating the line current of the motor based on the three-phase current of the motor in step S130 is further explained, including steps S310 to S330.

[0104] Step S310: Send a PWM signal to the inverter to turn on the inverter according to the first working state. After one current PWM carrier cycle, stop sending the PWM signal to the inverter, and calculate the line current of the motor based on the three-phase current of the motor obtained at this time, and use it as the first line current.

[0105] Step S320: After a delay of three current PWM carrier cycles, a PWM signal is sent to the inverter to turn on the inverter according to the second working state. After one current PWM carrier cycle, the sending of the PWM signal to the inverter is stopped, and the line current of the motor is calculated based on the three-phase current of the motor obtained at this time, which is used as the second line current.

[0106] In step S330, PWM signals are sent to the inverter in sequence according to the third, fourth, fifth and sixth working states to turn on the inverter, and the third line current, the fourth line current, the fifth line current and the sixth line current are obtained in sequence to obtain the line current of the motor.

[0107] like Figure 8 As shown, the specific implementation logic of the permanent magnet synchronous motor parameter identification method also includes:

[0108] Step 9: Sample the three-phase current, turn on the inverter according to the first operating state (A+B-), and after one time T, turn off the PWM output and calculate the line current I. ab Then proceed to step 10.

[0109] Step 10: Sample the three-phase current, delay for 3 T time (until the current returns to 0), turn on the inverter according to the second operating state (A-B+), and after one T time, turn off the PWM output and calculate the line current I. ba Then proceed to step 11.

[0110] Step 11: Sample the three-phase current, delay for 3 T time (until the current returns to 0), turn on the inverter according to the third operating state (B+C-), and after one T time, turn off the PWM output and calculate the line current I. bc Then proceed to step 12.

[0111] Step 12: Sample the three-phase current, delay for 3 T time (until the current returns to 0), turn on the inverter according to the fourth operating state (B-C+), and after one T time, turn off the PWM output and calculate the line current I. cb Then proceed to step 13.

[0112] Step 13: Sample the three-phase current, delay for 3 T time (until the current returns to 0), turn on the inverter according to the fifth operating state (C+A-), and after one T time, turn off the PWM output and calculate the line current I. ca Then proceed to step 14.

[0113] Step 14: Sample the three-phase current, delay for 3 T time (until the current returns to 0), turn on the inverter according to the sixth operating state (C-A+), and after one T time, turn off the PWM output and calculate the line current I. ac Then proceed to step 15.

[0114] Steps 9 to 14, after determining the minimum pulse width of the PWM wave, further obtain the line current I in the six simplified equivalent circuits.ab I ba I bc I cb I ca I ac Then, the motor parameters, including the direct-axis inductance L, are calculated using formulas. q L d With position angle θ e .

[0115] In the solution of this invention, after determining the pulse width of the next six PWM waves, the inverter is sequentially controlled to conduct the corresponding two-phase bridge arms according to the six preset conduction modes, the line current is recorded, and the line inductance of the permanent magnet synchronous motor is calculated to obtain the parameters to be identified. This can improve the identification accuracy and precision of the permanent magnet synchronous motor parameters and ensure the accuracy of motor parameter acquisition.

[0116] In step S140, the required parameters of the motor are calculated based on the line current of the motor.

[0117] The parameter identification scheme for permanent magnet synchronous motors proposed in this invention involves sequentially controlling the inverter to conduct corresponding two-phase bridge arms according to six preset conduction modes when the motor is stationary. The pulse width is adjusted based on the output current. When the maximum value of the three-phase current exceeds a current limit, the pulse width modulation (PWM) output is turned off, and the minimum value among the six pulse widths is recorded. This minimum pulse width is used as the pulse width for the next six PWM waves. The inverter is then sequentially controlled to conduct corresponding two-phase bridge arms according to the six preset conduction modes, and the line current is recorded. The line inductance of the permanent magnet synchronous motor is calculated to obtain the parameters to be identified. This method improves the accuracy and precision of permanent magnet synchronous motor parameter identification, ensuring the accuracy of motor parameter acquisition.

[0118] In some embodiments, the parameters of the motor include the position angle of the motor, and the quadrature-axis inductance and direct-axis inductance of the motor; the specific process of calculating the required parameters of the motor based on the line current of the motor in step S140, that is, calculating the position angle of the motor, and the quadrature-axis inductance and direct-axis inductance of the motor based on the line current of the motor as the required parameters of the motor, is described in the following exemplary description.

[0119] The following is combined with Figure 4 The flowchart shown is a schematic diagram of an embodiment of the method of the present invention in which the parameters of the motor to be determined are calculated based on the line current of the motor. The specific process of calculating the parameters of the motor to be determined based on the line current of the motor in step S140 is further explained, including steps S410 to S430.

[0120] Step S410: Calculate the line inductance of the motor based on the line current of the motor.

[0121] In some embodiments, the line current of the motor includes: a first line current, a second line current, a third line current, a fourth line current, a fifth line current, and a sixth line current, wherein the first line current is such that line current I. ab The second line current is like the line current I. ba The third line current is such as line current I. bc The fourth line current is such as line current I. cb The fifth line current is like the line current I. ca The sixth line current is like the line current I. ac The line inductance of the motor in step S410 includes: a first line inductance, a second line inductance, and a third line inductance; calculating the line inductance of the motor based on the line current includes: calculating the line inductance of the motor using the following formula based on the line current of the motor:

[0122]

[0123] Among them, L ab L bc L ca The three line inductances of the motor are, in order, the first line inductance, the second line inductance, and the third line inductance, U. dc I is the bus voltage on the input side of the inverter. ab For the first line current, I ba For the second line current, I bc For the third line current, I cb For the fourth line current, I ca For the fifth line current, I ac For the sixth line current, R S Let ΔT be the stator resistance of the motor, ΔT be the time delay, k1 be the first calculation coefficient (preferably k1 is 2), and k2 be the second calculation coefficient (preferably k2 is 0.5).

[0124] like Figure 8 As shown, the specific implementation logic of the permanent magnet synchronous motor parameter identification method also includes: Step 15, calculating the linear inductance L in the natural coordinate system. ab I bc L ca Then proceed to step 16.

[0125] Depend on Figure 7 The simplified equivalent circuit of the permanent magnet synchronous motor shown shows that the line inductance L line :

[0126]

[0127] Among them, U line For inductor L bc voltage, I line For inductor L bc The current; Δt is the time delay, which is the pulse width T of the minimum pulse width PWM wave in step 8.

[0128] Therefore, in the natural coordinate system, the inductance L ab L bc L ca The expression:

[0129]

[0130] Among them, line current:

[0131]

[0132] In the present invention, after obtaining the line current of the motor, the line inductance of the motor is calculated based on the line current, which serves as the reference for calculating the position angle of the motor, as well as the quadrature-axis inductance and direct-axis inductance of the motor. This can improve the identification accuracy and precision of the permanent magnet synchronous motor parameters, and ensure the accuracy of the motor parameter acquisition.

[0133] Step S420: Calculate the shaft inductance of the motor based on the line inductance of the motor; the shaft inductance of the motor includes: the quadrature shaft inductance and the direct shaft inductance of the motor.

[0134] Step S430: Calculate the position angle of the motor based on the shaft inductance of the motor; and use the calculated position angle of the motor, as well as the quadrature-axis inductance and direct-axis inductance of the motor, as the parameters of the motor to be determined.

[0135] In the solution of the present invention, after obtaining the line current of the motor, the position angle of the motor, as well as the quadrature-axis inductance and direct-axis inductance of the motor are calculated based on the line current of the motor, which are used as the parameters of the motor to be determined. This can improve the identification accuracy and precision of the permanent magnet synchronous motor parameters, and ensure the accuracy of the motor parameter acquisition.

[0136] In some embodiments, steps S420 and S430, calculating the shaft inductance of the motor based on its line inductance and calculating the position angle of the motor based on its shaft inductance, includes: calculating the shaft inductance and the position angle of the motor using the following formula based on the line inductance of the motor:

[0137]

[0138] Among them, L ab L bc L ca The three line inductances of the motor are, in order, the first line inductance, the second line inductance, and the third line inductance, L. d L is the quadrature-axis inductance of the motor. q Let θ be the direct-axis inductance of the motor. e Let k be the position angle of the motor, and k3 be the third calculation coefficient (preferably k3 is 2).

[0139] like Figure 8 As shown, the specific implementation logic of the permanent magnet synchronous motor parameter identification method also includes: Step 16, calculating the shaft inductance L. d L q Then proceed to step 17.

[0140] Inductance L in the natural coordinate system ab L bc L ca And shaft inductance L d L q The relationship between them is as follows:

[0141]

[0142] Let A = L d +L q B = L d -L q L0 = L ab -A, Then we have:

[0143]

[0144] Detailed calculations:

[0145]

[0146] Step 17: Calculate the position angle θ e .

[0147] make Then we have:

[0148]

[0149] Detailed calculations:

[0150]

[0151] θ among these parameters e That is, the motor position angle to be identified, L q Ld This refers to the desired AC and DC axis inductances of the motor. Formulas (1)-(4) illustrate the principle of line inductance calculation, where formula (1) is derived from... Figure 7 The circuit is readily available; Formula (5) is the current threshold calculation formula; Formulas (6)-(8) are the motor line inductance calculation formulas in this invention; Formula (9) is a known formula in the industry; Formulas (10)-(20) are the quadrature and direct axis inductance and position angle calculation formulas in this invention.

[0152] Among them, I e_motor I is the rated current of the motor. threshold This is the set current threshold that the motor current should reach; T1 to T6 are the times required for the maximum current value in the three-phase current to exceed the set current threshold under six operating conditions, i.e., the PWM waveform pulse width under the six operating conditions; T is the minimum pulse width among the six pulse widths T1 to T6; I ab I ba I bc I cb I ca I ac These are the line currents sampled in steps 9 to 14, respectively; L ab L bc L ca These are the line inductances of the motor; U dc L is the bus voltage of the motor controller. d L q These are the direct-axis and quadrature-axis inductances of the motor, respectively, and Theta_t (i.e., θ) t ) or θ e Here, θ represents the motor position angle; A, B, L0, L1, M0, M1, and M2 are the parameters to be identified for ease of calculation: the direct and quadrature axis inductances Lq and Ld, and the position angle θ. e The intermediate variables defined have no special meaning.

[0153] In the present invention, the shaft inductance of the motor is calculated based on the line inductance of the motor, and the position angle of the motor is calculated based on the shaft inductance of the motor. This can improve the identification accuracy and precision of the permanent magnet synchronous motor parameters, and ensure the accuracy of the motor parameter acquisition.

[0154] The present invention proposes a parameter identification scheme for permanent magnet synchronous motors, applicable not only to the electric vehicle field but also to other permanent magnet synchronous motor applications such as CNC machine tools, mechanical manufacturing, industrial robots, and aerospace. Using this scheme improves the accuracy and precision of permanent magnet synchronous motor parameter identification, facilitates rapid matching between the motor controller and the permanent magnet synchronous motor, enables precise motor control, ensures efficient motor operation, and enhances the robustness of the control system. This method simplifies the calculation process, is easy to implement, provides reliable control, is easy to carry out, and is readily promoted and used.

[0155] Using the technical solution of this embodiment, when the motor (such as a permanent magnet synchronous motor) is stationary, the six bridge arms of the inverter are turned on in a preset manner. The pulse width is adjusted according to the output current. When the maximum value of the three-phase current is greater than the current limit, the PWM output is turned off, and the minimum value among the six pulse widths is recorded to determine the minimum pulse width T of the PWM wave. The minimum value of the minimum pulse width T of the PWM wave is used as the pulse width of the next six PWM waves. The inverter is controlled to turn on the corresponding two-phase bridge arms in six preset conduction modes in sequence, and the line current is recorded. The line inductance of the permanent magnet synchronous motor is calculated to obtain the AC and DC axis inductance L of the motor. q L d With position angle θ e In order to obtain the parameters to be identified, by controlling the six bridge arms of the inverter to conduct in a preset manner, the parameters to be identified can be calculated based on the obtained line current, thereby improving the identification accuracy and precision of motor parameters.

[0156] According to an embodiment of the present invention, a parameter determination apparatus for a motor, corresponding to a method for determining motor parameters, is also provided. See also Figure 5 The diagram shows a structural schematic of an embodiment of the device of the present invention. The motor has a drive system and three-phase windings; the drive system of the motor has an inverter, the inverter has a three-phase full-bridge inverter bridge composed of a first switch, a second switch, a third switch, a fourth switch, a fifth switch and a sixth switch, the first switch and the fourth switch are the upper and lower bridge arm switches of the A-phase bridge arm, and are used to supply power to the U-phase winding of the three-phase windings of the motor, the third switch and the sixth switch are the upper and lower bridge arm switches of the B-phase bridge arm, and are used to supply power to the V-phase winding of the three-phase windings of the motor, the fifth switch and the second switch are the upper and lower bridge arm switches of the C-phase bridge arm, and are used to supply power to the W-phase winding of the three-phase windings of the motor, the first switch is VT1, the second switch is VT2, the third switch is VT3, the fourth switch is VT4, the fifth switch is VT5, and the sixth switch is VT6. Figure 6This is a schematic diagram of a permanent magnet synchronous motor drive system based on a three-phase voltage source inverter. Figure 6 The permanent magnet synchronous motor drive system based on a three-phase voltage source inverter shown includes: a rectifier, a bus capacitor, and an inverter. The rectifier consists of a full-bridge diode rectifier composed of six diodes, and the voltage across the bus capacitor is the bus voltage U. DC The inverter is a full-bridge inverter consisting of six switching transistors VT1, VT2, VT3, VT4, VT5 to VT6, each with a freewheeling diode. VT1 and VT4 are the upper and lower transistors of the A-phase bridge arm, VT3 and VT6 are the upper and lower transistors of the B-phase bridge arm, and VT5 and VT2 are the upper and lower transistors of the C-phase bridge arm. The permanent magnet synchronous motor drive system based on a three-phase voltage source inverter, after rectification and inversion of the three-phase AC power, provides three-phase current i to the motor's three-phase windings u, v, and w. A i B and i C .

[0157] In some embodiments, the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter are turned on in a preset manner. This means controlling the upper and lower arm switches of the A-phase bridge arm, the B-phase bridge arm, and the C-phase bridge arm to sequentially put the inverter into a first operating state, a second operating state, a third operating state, a fourth operating state, a fifth operating state, and a sixth operating state.

[0158] The first operating state is as follows: the upper bridge arm switch of phase A of the inverter is turned on and the lower bridge arm switch is turned off; the upper bridge arm switch of phase B is turned off and the lower bridge arm switch is turned on; and the upper and lower bridge arm switches of phase C are both turned off.

[0159] The second operating state is as follows: the upper bridge arm switch of phase A of the inverter is turned off and the lower bridge arm switch is turned on; the upper bridge arm switch of phase B is turned on and the lower bridge arm switch is turned off; and both the upper and lower bridge arm switches of phase C are turned off.

[0160] The third operating state is as follows: the upper and lower bridge arm switches of the A-phase bridge arm of the inverter are both off, the upper bridge arm switch of the B-phase bridge arm is on and the lower bridge arm switch is off, and the upper bridge arm switch of the C-phase bridge arm is off and the lower bridge arm switch is on.

[0161] The fourth operating state is as follows: the upper and lower bridge arm switches of the A-phase bridge arm of the inverter are both off, the upper bridge arm switch of the B-phase bridge arm is off and the lower bridge arm switch is on, and the upper bridge arm switch of the C-phase bridge arm is on and the lower bridge arm switch is off.

[0162] The fifth operating state is as follows: the upper bridge arm switch of the A phase bridge arm of the inverter is turned off and the lower bridge arm switch is turned on; both the upper and lower bridge arm switches of the B phase bridge arm are turned off; and the upper bridge arm switch of the C phase bridge arm is turned on and the lower bridge arm switch is turned off.

[0163] The sixth operating state is as follows: the upper bridge arm switch of the A phase bridge arm of the inverter is turned on and the lower bridge arm switch is turned off; both the upper and lower bridge arm switches of the B phase bridge arm are turned off; and the upper bridge arm switch of the C phase bridge arm is turned off and the lower bridge arm switch is turned on.

[0164] Figure 6 The inverter uses upper and lower tube commutation. In the scheme of this invention, seven working states are defined, namely the first working state, the second working state, the third working state, the fourth working state, the fifth working state, the sixth working state, and the seventh working state.

[0165] The first working state is as follows: the upper tube of phase A is on and the lower tube is off; the upper tube of phase B is off and the lower tube is on; and both the upper and lower tubes of phase C are off. That is, VT1 and VT6 are on, and the rest are off.

[0166] The second operating state: Phase A upper tube is off and lower tube is on, Phase B upper tube is on and lower tube is off, and Phase C both upper and lower tubes are off; that is, VT4 and VT3 are on, and the rest are off.

[0167] The third operating state: both the upper and lower tubes of phase A are off, the upper tube of phase B is on and the lower tube is off, the upper tube of phase C is off and the lower tube is on; that is, VT3 and VT2 are on, and the rest are off.

[0168] The fourth operating state: both the upper and lower tubes of phase A are off, the upper tube of phase B is off and the lower tube is on, the upper tube of phase C is on and the lower tube is off; that is, VT6 and VT5 are on, and the rest are off.

[0169] The fifth operating state: Phase A upper tube is off and lower tube is on; Phase B upper and lower tubes are both off; Phase C upper tube is on and lower tube is off; that is, VT4 and VT5 are on, and the rest are off.

[0170] The sixth operating state: Phase A upper tube is on and lower tube is off; Phase B upper and lower tubes are both off; Phase C upper tube is off and lower tube is on; that is, VT1 and VT2 are on, and the rest are off.

[0171] The seventh operating state: all three power devices (A, B, and C) are turned off.

[0172] In the present invention, when the motor is stationary, the inverter is sequentially controlled to conduct the corresponding two-phase bridge arms according to six preset conduction modes. Then, the pulse width is adjusted according to the output current, and the line current of the motor is obtained. Then, the line inductance of the permanent magnet synchronous motor is calculated to obtain the parameters to be identified. This can improve the identification accuracy and precision of the permanent magnet synchronous motor parameters and ensure the accuracy of the motor parameter acquisition.

[0173] In the solution of the present invention, such as Figure 5 As shown, the parameter determination device for the motor includes: an acquisition unit 102 and a control unit 104.

[0174] The acquisition unit 102 is configured to acquire a pre-set PWM carrier period as the initial PWM carrier period; and to acquire the rated current of the motor, such as the rated current I of a permanent magnet synchronous motor. e_motor Furthermore, when the inverter is turned on, the three-phase currents (such as currents Ia, Ib, and Ic) of the motor are acquired. For the specific functions and processing of this acquisition unit 102, please refer to step S110.

[0175] The control unit 104 is configured to, when the motor is stationary, control the motor controller to send a drive signal to the motor drive system, i.e., to send a PWM signal to the inverter, according to the initial PWM carrier cycle. This controls the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter to conduct in a preset manner. This is to update the initial PWM carrier cycle by combining the rated current of the motor and the three-phase current of the motor obtained when controlling the inverter according to the initial PWM carrier cycle, thus obtaining the current PWM carrier cycle. Specifically, during the process of controlling the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter to conduct in a preset manner, the three-phase current of the motor is acquired, and the pulse width of the PWM signal is recorded. Then, based on the three-phase current of the motor and the pulse width of the PWM signal, the initial PWM carrier cycle is updated to obtain the current PWM carrier cycle. For the specific functions and processing of the control unit 104, please refer to step S120.

[0176] In some embodiments, after the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter are turned on in a preset manner, the inverter can be in any one of the following operating states: a first operating state, a second operating state, a third operating state, a fourth operating state, a fifth operating state, and a sixth operating state. The control unit 104 sends a PWM signal to the inverter to control the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter to be turned on in a preset manner, so as to: update the initial PWM carrier cycle by combining the rated current of the motor and the three-phase current of the motor obtained when controlling the inverter according to the initial PWM carrier cycle, to obtain the current PWM carrier cycle, including:

[0177] The control unit 104 is further configured to determine a current threshold for the motor based on its rated current. Specifically, it determines the rated current I of the motor. e_motor The set coefficient multiple is determined as the current threshold I of the motor. threshold The set coefficient is 0.8. For the specific functions and processing of the control unit 104, please refer to step S210.

[0178] The control unit 104 is further configured to send a PWM signal to the inverter to turn on the inverter according to the first operating state, and then adjust the pulse width of the PWM signal until the maximum value of the three-phase current of the motor is greater than the current threshold of the motor, at which point it stops sending the PWM signal to the inverter and records the pulse width of the PWM signal at this time as the first pulse width of the PWM signal. The specific functions and processing of the control unit 104 are further described in step S220.

[0179] The control unit 104 is further configured to delay for a period of time until the three-phase current of the motor is obtained to 0, then send a PWM signal to the inverter to turn on the inverter according to the second operating state. Afterwards, the pulse width of the PWM signal is adjusted until the maximum value of the three-phase current of the motor is greater than the current threshold of the motor, at which point the sending of the PWM signal to the inverter stops, and the pulse width of the PWM signal at this time is recorded as the second pulse width of the PWM signal. The specific functions and processing of this control unit 104 are further described in step S230.

[0180] The control unit 104 is further configured to sequentially send PWM signals to the inverter to turn on the inverter according to the third, fourth, fifth, and sixth operating states, and sequentially obtain the third, fourth, fifth, and sixth pulse widths of the PWM signals. Specifically, the first pulse width of the PWM signal is as shown in pulse width T1, the second pulse width is as shown in pulse width T2, the third pulse width is as shown in pulse width T3, the fourth pulse width is as shown in pulse width T4, the fifth pulse width is as shown in pulse width T5, and the sixth pulse width is as shown in pulse width T6. The specific functions and processing of the control unit 104 are further described in step S240.

[0181] The control unit 104 is further configured to delay for a period of time until the obtained three-phase current of the motor is 0, then determine the minimum pulse width among the first pulse width, second pulse width, third pulse width, fourth pulse width, fifth pulse width, and sixth pulse width of the PWM signal, in order to update the initial PWM carrier period and obtain the current PWM carrier period. The specific functions and processing of this control unit 104 are further described in step S250.

[0182] Figure 7 A simplified equivalent circuit diagram for a permanent magnet synchronous motor. (Example) Figure 7 As shown, the simplified equivalent circuit of the permanent magnet synchronous motor includes: a power supply, a switch S, a diode D, a resistor R, and an inductor Lbc. The power supply voltage is v_dc. The positive terminal of the power supply is connected to the negative terminal of the power supply via the switch S, resistor R, and inductor Lbc; the negative terminal of the power supply is grounded to GND. The anode of diode D is connected to the common terminal between the switch S and the resistor R; the cathode of diode D is grounded to GND. The resistance of resistor R is R = 2Rs, where Rs is the resistance of the motor stator.

[0183] like Figure 6 As shown, disconnect phase A of the motor and connect phases B and C to the positive and negative terminals of the DC power supply, respectively. Fix the motor rotor. At this point, the system simplifies to an RL circuit, i.e. Figure 7 As shown. Where the power supply voltage v_dc is the bus voltage of the motor controller, the resistance R is twice the stator resistance Rs of the motor, and the inductance Lbc is the stator line inductance. When switch S is closed, the voltage u and current i in the RL circuit satisfy:

[0184]

[0185] Among them, L line This is the inductance value of the stator line inductance.

[0186] Because the stator resistance of a high-power motor is relatively small, R*i can be ignored when the current is small, and the above formula can be simplified to:

[0187]

[0188] Therefore, we can conclude that:

[0189] L line =∫udt / i (3)

[0190] That is, inductance L line It equals the integral of voltage u divided by inductance L line When the input voltage U is constant, the current i in the equation can be simplified to:

[0191] L line =U*t / i (4)

[0192] At this time, the inductance L line The current i and voltage U in the RL are linearly related, and this linear relationship only holds true when the current i is very small, that is, in the initial stage of the RL inertial response.

[0193] Where R is the resistance value in the simplified equivalent circuit of the motor, which is twice the stator resistance Rs of the motor; u is the total load voltage in the equivalent circuit; i is the current flowing through the equivalent circuit; L line It is a line inductance, that is Figure 7 The L shown bc t represents the initial stage of the RL inertial response.

[0194] Figure 8 This is a flowchart illustrating the parameter identification method for permanent magnet synchronous motors. Figure 8 As shown, the specific implementation logic of the permanent magnet synchronous motor parameter identification method includes:

[0195] Step 1: Initialize all parameter variables, set the PWM carrier period, and determine the period based on the rated current I of the permanent magnet synchronous motor. e_motor Calculate the current threshold I threshold Then proceed to step 2. This involves determining the rated current I of the permanent magnet synchronous motor. e_motor Calculate the current threshold I threshold The method is as follows:

[0196] I threshold =0.8*I e_motor (5).

[0197] Step 2: Enable PWM output, sample three-phase current, and turn on the inverter according to the first operating state (A+B-). Perform pulse width detection and adjustment. When the maximum value of the three-phase current is greater than the set current threshold I... thresholdWhen the PWM output is turned off, the pulse width T1 at this time is recorded, and then step 3 is executed. Among them, the first working state (A+B-) means that the upper tube of phase A is on and the lower tube is off, the upper tube of phase B is off and the lower tube is on, and both the upper and lower tubes of phase C are off.

[0198] Step 3: Sample the three-phase current, delay for a period of time (until the current returns to 0), and turn on the inverter according to the second operating state (A-B+). Perform pulse width detection and adjustment. When the maximum value of the three-phase current is greater than the set current threshold, turn off the PWM output and record the pulse width T2 at this time. Then execute step 4. The two operating states (A-B+) are: A-phase upper transistor off and lower transistor on, B-phase upper transistor on and lower transistor off, and C-phase both upper and lower transistors off.

[0199] Step 4: Sample the three-phase current, delay for a period of time (until the current returns to 0), and turn on the inverter according to the third operating state (B+C-). Perform pulse width detection and adjustment. When the maximum value of the three-phase current is greater than the set current threshold, turn off the PWM output and record the pulse width T3 at this time. Then execute step 5. The third operating state (B+C-) means that the upper and lower transistors of phase A are both off, the upper transistor of phase B is on and the lower transistor is off, and the upper transistor of phase C is off and the lower transistor is on.

[0200] Step 5: Sample the three-phase current, delay for a period of time (until the current returns to 0), and turn on the inverter according to the fourth operating state (B-C+). Perform pulse width detection and adjustment. When the maximum value of the three-phase current is greater than the set current threshold, turn off the PWM output and record the pulse width T4 at this time. Then execute step 6. The fourth operating state (B-C+) means that both the upper and lower transistors of phase A are off, the upper transistor of phase B is off and the lower transistor is on, and the upper transistor of phase C is on and the lower transistor is off.

[0201] Step 6: Sample the three-phase current, delay for a period of time (until the current returns to 0), and turn on the inverter according to the fifth operating state (C+A-). Perform pulse width detection and adjustment. When the maximum value of the three-phase current is greater than the set current threshold, turn off the PWM output and record the pulse width T5 at this time. Then execute step 7. The fifth operating state (C+A-) means that the upper transistor of phase A is off and the lower transistor is on, both the upper and lower transistors of phase B are off, and the upper transistor of phase C is on and the lower transistor is off.

[0202] Step 7: Sample the three-phase current, delay for a period of time (until the current returns to 0), and turn on the inverter according to the sixth operating state (C-A+). Perform pulse width detection and adjustment. When the maximum value of the three-phase current is greater than the set current threshold, turn off the PWM output and record the pulse width T6 at this time. Then execute step 8. The sixth operating state (C-A+) means that the upper transistor of phase A is on and the lower transistor is off, both the upper and lower transistors of phase B are off, and the upper transistor of phase C is off and the lower transistor is on.

[0203] Step 8: After a delay until the current returns to 0, select the smallest pulse width among the six pulse widths as the pulse width T of the PWM wave, i.e., T = min(T1, T2, T3, T4, T5, T6); set T as the period of the PWM carrier wave, and then execute step 9.

[0204] From the Figure 7 As described, in the simplified equivalent circuit of the motor, when the current is small, especially when the input voltage is constant, the inductor current and voltage exhibit a linear relationship. When the voltage pulse width is small, the current changes almost linearly; when the current is turned off, the current decreases slowly. Steps 2 to 7 respectively follow the preset conduction states, causing the six bridge arms of the inverter to conduct in a preset manner, achieving the desired effect. Figure 7 The simplified RL circuit described in the system is used to determine the minimum pulse width T of the PWM wave. Because the presence of stray inductance, parasitic inductance, stray capacitance, and parasitic capacitance in the entire system can cause inconsistencies in the time it takes for the maximum current in the three phases to reach the set threshold current, i.e., inconsistent PWM wave pulse width times, steps 2 to 7 are used to eliminate the influence of stray inductance, parasitic inductance, stray capacitance, and parasitic capacitance on the line inductance. The minimum pulse width T is the required pulse width. The delay in each step is to allow the current in the circuit to return to zero, meaning that only a single current generated by a single wave exists in the circuit each time.

[0205] In the present invention, when the motor is stationary, the inverter is sequentially controlled to conduct the corresponding two-phase bridge arms according to six preset conduction modes. The pulse width is adjusted according to the output current. When the maximum value of the three-phase current is greater than the current limit, the PWM output is turned off, and the pulse width is recorded to obtain the minimum value among the six pulse widths. This minimum pulse width is used as the pulse width for the next six PWM waves, thereby obtaining the line current of the motor. The line inductance of the permanent magnet synchronous motor is calculated to obtain the parameters to be identified. This can improve the identification accuracy and precision of the permanent magnet synchronous motor parameters, and ensure the accuracy of motor parameter acquisition.

[0206] The control unit 104 is further configured to, according to the current PWM carrier cycle, again control the motor controller to send a drive signal to the motor drive system, that is, to send a PWM signal to the inverter again, and again control the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter to conduct in a preset manner, so as to calculate the line current of the motor based on the three-phase current of the motor obtained when controlling the inverter according to the initial PWM carrier cycle. The specific functions and processing of this control unit 104 are further described in step S130.

[0207] In some embodiments, after the upper and lower arms of phase A, phase B, and phase C of the inverter are turned on according to a preset method, the inverter can be in any one of the following operating states: a first operating state, a second operating state, a third operating state, a fourth operating state, a fifth operating state, and a sixth operating state. The line current of the motor includes: a first line current, a second line current, a third line current, a fourth line current, a fifth line current, and a sixth line current, wherein the first line current is such that line current I... ab The second line current is like the line current I. ba The third line current is such as line current I. bc The fourth line current is such as line current I. cb The fifth line current is like the line current I. ca The sixth line current is like the line current I. ac The control unit 104 sends a PWM signal to the inverter again, and controls the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter to conduct in a preset manner, so as to calculate the line current of the motor based on the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle, including:

[0208] The control unit 104 is further configured to send a PWM signal to the inverter to turn on the inverter according to the first operating state, and after one current PWM carrier cycle, stop sending the PWM signal to the inverter, and calculate the line current of the motor based on the three-phase current of the motor obtained at this time, as the first line current. The specific functions and processing of the control unit 104 are also described in step S310.

[0209] The control unit 104 is further configured to, after a delay of three current PWM carrier cycles, send a PWM signal to the inverter to turn it on according to the second operating state; after one current PWM carrier cycle, stop sending the PWM signal to the inverter, and calculate the line current of the motor based on the three-phase current of the motor obtained at this time, as the second line current. The specific functions and processing of this control unit 104 are further described in step S320.

[0210] The control unit 104 is further configured to sequentially send PWM signals to the inverter to turn on the inverter according to the third, fourth, fifth, and sixth operating states, and sequentially obtain the third, fourth, fifth, and sixth line currents to obtain the line current of the motor. The specific functions and processing of the control unit 104 are further described in step S330.

[0211] like Figure 8 As shown, the specific implementation logic of the permanent magnet synchronous motor parameter identification method also includes:

[0212] Step 9: Sample the three-phase current, turn on the inverter according to the first operating state (A+B-), and after one time T, turn off the PWM output and calculate the line current I. ab Then proceed to step 10.

[0213] Step 10: Sample the three-phase current, delay for 3 T time (until the current returns to 0), turn on the inverter according to the second operating state (A-B+), and after one T time, turn off the PWM output and calculate the line current I. ba Then proceed to step 11.

[0214] Step 11: Sample the three-phase current, delay for 3 T time (until the current returns to 0), turn on the inverter according to the third operating state (B+C-), and after one T time, turn off the PWM output and calculate the line current I. bc Then proceed to step 12.

[0215] Step 12: Sample the three-phase current, delay for 3 T time (until the current returns to 0), turn on the inverter according to the fourth operating state (B-C+), and after one T time, turn off the PWM output and calculate the line current L. cb Then proceed to step 13.

[0216] Step 13: Sample the three-phase current, delay for 3 T time (until the current returns to 0), turn on the inverter according to the fifth operating state (C+A-), and after one T time, turn off the PWM output and calculate the line current I. ca Then proceed to step 14.

[0217] Step 14: Sample the three-phase current, delay for 3 T time (until the current returns to 0), turn on the inverter according to the sixth operating state (C-A+), and after one T time, turn off the PWM output and calculate the line current I. ac Then proceed to step 15.

[0218] Steps 9 to 14, after determining the minimum pulse width of the PWM wave, further obtain the line current I in the six simplified equivalent circuits. ab I ba I bc I cb I ca I ac Then, the motor parameters, including the direct-axis inductance L, are calculated using formulas. q L d With position angle θ e .

[0219] In the solution of this invention, after determining the pulse width of the next six PWM waves, the inverter is sequentially controlled to conduct the corresponding two-phase bridge arms according to the six preset conduction modes, the line current is recorded, and the line inductance of the permanent magnet synchronous motor is calculated to obtain the parameters to be identified. This can improve the identification accuracy and precision of the permanent magnet synchronous motor parameters and ensure the accuracy of motor parameter acquisition.

[0220] The control unit 104 is further configured to calculate the required parameters of the motor based on the line current of the motor. The specific functions and processing of the control unit 104 are further described in step S140.

[0221] The parameter identification scheme for permanent magnet synchronous motors proposed in this invention involves sequentially controlling the inverter to conduct corresponding two-phase bridge arms according to six preset conduction modes when the motor is stationary. The pulse width is adjusted based on the output current. When the maximum value of the three-phase current exceeds a current limit, the pulse width modulation (PWM) output is turned off, and the minimum value among the six pulse widths is recorded. This minimum pulse width is used as the pulse width for the next six PWM waves. The inverter is then sequentially controlled to conduct corresponding two-phase bridge arms according to the six preset conduction modes, and the line current is recorded. The line inductance of the permanent magnet synchronous motor is calculated to obtain the parameters to be identified. This method improves the accuracy and precision of permanent magnet synchronous motor parameter identification, ensuring the accuracy of motor parameter acquisition.

[0222] In some embodiments, the parameters of the motor include the motor's position angle, and the motor's quadrature-axis inductance and direct-axis inductance; the control unit 104 calculates the required parameters of the motor based on the motor's line current, that is, it calculates the motor's position angle, and the motor's quadrature-axis inductance and direct-axis inductance based on the motor's line current, as the required parameters of the motor, including:

[0223] The control unit 104 is further configured to calculate the line inductance of the motor based on the line current of the motor. The specific functions and processing of the control unit 104 are further described in step S410.

[0224] In some embodiments, the line current of the motor includes: a first line current, a second line current, a third line current, a fourth line current, a fifth line current, and a sixth line current, wherein the first line current is such that line current I. ab The second line current is like the line current I. ba The third line current is such as line current I. bc The fourth line current is such as line current I. cb The fifth line current is like the line current I. ca The sixth line current is such as the line current L. ac The control unit 104, the line inductance of the motor, includes: a first line inductance, a second line inductance, and a third line inductance; calculating the line inductance of the motor based on the line current of the motor includes: the control unit 104 is further configured to calculate the line inductance of the motor based on the line current of the motor using the following formula:

[0225]

[0226] Among them, L ab L bc L ca The three line inductances of the motor are, in order, the first line inductance, the second line inductance, and the third line inductance, U. dc I is the bus voltage on the input side of the inverter. ab For the first line current, I ba For the second line current, I bc For the third line current, I cb For the fourth line current, I ca For the fifth line current, I ac For the sixth line current, R S Let ΔT be the stator resistance of the motor, ΔT be the time delay, k1 be the first calculation coefficient (preferably k1 is 2), and k2 be the second calculation coefficient (preferably k2 is 0.5).

[0227] like Figure 8 As shown, the specific implementation logic of the permanent magnet synchronous motor parameter identification method also includes: Step 15, calculating the linear inductance L in the natural coordinate system. ab L bc L ca Then proceed to step 16.

[0228] Depend on Figure 7The simplified equivalent circuit of the permanent magnet synchronous motor shown shows that the line inductance L line :

[0229]

[0230] Among them, U line For inductor L bc voltage, I line For inductor L bc The current is Δt, which is the time delay.

[0231] Therefore, in the natural coordinate system, the inductance L ab L bc L ca The expression:

[0232]

[0233] Among them, line current:

[0234]

[0235] In the present invention, after obtaining the line current of the motor, the line inductance of the motor is calculated based on the line current, which serves as the reference for calculating the position angle of the motor, as well as the quadrature-axis inductance and direct-axis inductance of the motor. This can improve the identification accuracy and precision of the permanent magnet synchronous motor parameters, and ensure the accuracy of the motor parameter acquisition.

[0236] The control unit 104 is further configured to calculate the shaft inductance of the motor based on the line inductance of the motor; the shaft inductance of the motor includes the quadrature-axis inductance and the direct-axis inductance of the motor. The specific functions and processing of the control unit 104 are further described in step S420.

[0237] The control unit 104 is further configured to calculate the position angle of the motor based on the motor's shaft inductance; and to use the calculated position angle, quadrature-axis inductance, and direct-axis inductance of the motor as parameters of the motor to be determined. The specific functions and processing of this control unit 104 are further described in step S430.

[0238] In the solution of the present invention, after obtaining the line current of the motor, the position angle of the motor, as well as the quadrature-axis inductance and direct-axis inductance of the motor are calculated based on the line current of the motor, which are used as the parameters of the motor to be determined. This can improve the identification accuracy and precision of the permanent magnet synchronous motor parameters, and ensure the accuracy of the motor parameter acquisition.

[0239] In some embodiments, the control unit 104 calculates the shaft inductance of the motor based on the line inductance of the motor, and calculates the position angle of the motor based on the shaft inductance of the motor, including: the control unit 104 is further configured to calculate the shaft inductance of the motor and the position angle of the motor based on the line inductance of the motor using the following formula:

[0240]

[0241] Among them, L ab L bc L ca The three line inductances of the motor are, in order, the first line inductance, the second line inductance, and the third line inductance, L. d L is the quadrature-axis inductance of the motor. q Let θ be the direct-axis inductance of the motor. e Let k be the position angle of the motor, and k3 be the third calculation coefficient (preferably k3 is 2).

[0242] like Figure 8 As shown, the specific implementation logic of the permanent magnet synchronous motor parameter identification method also includes: Step 16, calculating the shaft inductance L. d L q Then proceed to step 17.

[0243] Inductance L in the natural coordinate system ab L bc L ca And shaft inductance L d L q The relationship between them is as follows:

[0244]

[0245] Let A = L d +L q B = L d -L q L0 = L ab -A, Then we have:

[0246]

[0247] Detailed calculations:

[0248]

[0249] Step 17: Calculate the position angle θ e .

[0250] make Then we have:

[0251]

[0252] Detailed calculations:

[0253]

[0254] θ among these parameters e That is, the motor position angle to be identified, L q L d This refers to the AC and DC axis inductances of the motor that we want to obtain.

[0255] Among them, I e_motor I is the rated current of the motor. threshold This is the set current threshold that the motor current should reach; T1 to T6 are the times required for the maximum current value in the three-phase current to exceed the set current threshold under six operating conditions, i.e., the PWM waveform pulse width under the six operating conditions; T is the minimum pulse width among the six pulse widths T1 to T6; I ab I ba I bc I cb I ca I ac These are the line currents sampled in steps 9 to 14, respectively; L ab L bc L ca These are the line inductances of the motor; U dc L is the bus voltage of the motor controller. d L q These are the direct-axis and quadrature-axis inductances of the motor, respectively, and Theta_t and θ. e Here, θ represents the motor position angle; A, B, L0, L1, M0, M1, and M2 are the parameters to be identified for ease of calculation: the direct and quadrature axis inductances Lq and Ld, and the position angle θ. e The intermediate variables defined have no special meaning.

[0256] In the present invention, the shaft inductance of the motor is calculated based on the line inductance of the motor, and the position angle of the motor is calculated based on the shaft inductance of the motor. This can improve the identification accuracy and precision of the permanent magnet synchronous motor parameters, and ensure the accuracy of the motor parameter acquisition.

[0257] The present invention proposes a parameter identification scheme for permanent magnet synchronous motors, applicable not only to the electric vehicle field but also to other permanent magnet synchronous motor applications such as CNC machine tools, mechanical manufacturing, industrial robots, and aerospace. Using this scheme improves the accuracy and precision of permanent magnet synchronous motor parameter identification, facilitates rapid matching between the motor controller and the permanent magnet synchronous motor, enables precise motor control, ensures efficient motor operation, and enhances the robustness of the control system. This method simplifies the calculation process, is easy to implement, provides reliable control, is easy to carry out, and is readily promoted and used.

[0258] Since the processing and functions implemented by the device in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned methods, any details not covered in the description of this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0259] According to an embodiment of the present invention, a motor corresponding to a parameter determining device for a motor is also provided. This motor may include the parameter determining device for the motor described above.

[0260] Since the processing and functions implemented by the motor in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned device, any details not covered in this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0261] According to an embodiment of the present invention, a computer program product corresponding to an electric motor is also provided, including a computer program that, when executed by a processor, implements the steps of the above-described method for determining the parameters of the electric motor.

[0262] Since the processing and functions implemented by the product in this embodiment are basically the same as those of the aforementioned motor embodiments, principles and examples, any details not covered in this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0263] According to an embodiment of the present invention, a storage medium corresponding to a method for determining the parameters of a motor is also provided. The storage medium includes a stored program, wherein, when the program is executed, the device where the storage medium is located executes the steps of the method for determining the parameters of the motor described above.

[0264] Since the processing and functions implemented by the storage medium in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned methods, any details not covered in this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0265] In summary, it is readily understood by those skilled in the art that, without conflict, the aforementioned advantageous methods can be freely combined and superimposed.

[0266] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A method for determining the parameters of an electric motor, characterized in that, The motor has a drive system and three-phase windings; the drive system of the motor has an inverter, the inverter having a three-phase full-bridge inverter bridge composed of a first switch, a second switch, a third switch, a fourth switch, a fifth switch, and a sixth switch; the first switch and the fourth switch are the upper and lower bridge arm switches of the A-phase bridge arm, and are used to supply power to the U-phase winding of the motor's three-phase windings; the third switch and the sixth switch are the upper and lower bridge arm switches of the B-phase bridge arm, and are used to supply power to the V-phase winding of the motor's three-phase windings; the fifth switch and the second switch are the upper and lower bridge arm switches of the C-phase bridge arm, and are used to supply power to the W-phase winding of the motor's three-phase windings; the method for determining the parameters of the motor includes: Obtain a pre-set PWM carrier period as the initial PWM carrier period; obtain the rated current of the motor; and, when the inverter is turned on, obtain the three-phase current of the motor. With the motor stationary, a PWM signal is sent to the inverter according to the initial PWM carrier cycle to control the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter to conduct in a preset manner. This is to update the initial PWM carrier cycle by combining the rated current of the motor and the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle, and obtain the current PWM carrier cycle. The pulse width is then adjusted according to the output current. When the maximum value of the three-phase current is greater than the current limit, the PWM output is turned off, and the pulse width is recorded to obtain the minimum value among six pulse widths to determine the minimum pulse width T of the PWM wave. The minimum pulse width T of the PWM wave is used as the pulse width of the next six PWM waves. According to the current PWM carrier cycle, the PWM signal is sent to the inverter again, and the upper and lower bridge arms of the A-phase bridge arm, the upper and lower bridge arms of the B-phase bridge arm, and the upper and lower bridge arms of the C-phase bridge arm of the inverter are controlled to conduct in a preset manner. Based on the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle, the line current of the motor is calculated. The line current of the motor includes: a first line current, a second line current, a third line current, a fourth line current, a fifth line current, and a sixth line current; based on the line current of the motor, the required parameters of the motor are calculated, including: The line inductance of the motor is calculated using the following formula based on the line current of the motor: Among them, L ab L bc L ca The three line inductances of the motor are, in order, the first line inductance, the second line inductance, and the third line inductance, U. dc I is the bus voltage on the input side of the inverter. ab For the first line current, I ba For the second line current, I bc For the third line current, I cb For the fourth line current, I ca For the fifth line current, I ac For the sixth line current, R S The value of the stator resistance of the motor is given by ΔT, where ΔT is the time delay, k1 is the first calculation coefficient, and k2 is the second calculation coefficient. The line inductance of the motor includes: a first line inductance, a second line inductance, and a third line inductance.

2. The method for determining the parameters of a motor according to claim 1, characterized in that, The upper and lower arms of phase A, phase B, and phase C of the inverter are turned on in a preset manner. This means controlling the upper and lower arm switches of phase A, phase B, and phase C to sequentially operate the inverter in six different states: a first operating state, a second operating state, a third operating state, a fourth operating state, a fifth operating state, and a sixth operating state. The first operating state is as follows: the upper bridge arm switch of the A phase bridge arm of the inverter is turned on and the lower bridge arm switch is turned off; the upper bridge arm switch of the B phase bridge arm is turned off and the lower bridge arm switch is turned on; and the upper and lower bridge arm switches of the C phase bridge arm are both turned off. The second operating state is as follows: the upper bridge arm switch of the A phase bridge arm of the inverter is turned off and the lower bridge arm switch is turned on; the upper bridge arm switch of the B phase bridge arm is turned on and the lower bridge arm switch is turned off; and both the upper and lower bridge arm switches of the C phase bridge arm are turned off. The third operating state is as follows: the upper and lower bridge arm switches of the A phase bridge arm of the inverter are both turned off, the upper bridge arm switch of the B phase bridge arm is turned on and the lower bridge arm switch is turned off, and the upper bridge arm switch of the C phase bridge arm is turned off and the lower bridge arm switch is turned on. The fourth operating state is as follows: the upper and lower bridge arm switches of the A phase bridge arm of the inverter are both turned off, the upper bridge arm switch of the B phase bridge arm is turned off and the lower bridge arm switch is turned on, and the upper bridge arm switch of the C phase bridge arm is turned on and the lower bridge arm switch is turned off. The fifth operating state is as follows: the upper bridge arm switch of the A phase bridge arm of the inverter is turned off and the lower bridge arm switch is turned on; both the upper and lower bridge arm switches of the B phase bridge arm are turned off; and the upper bridge arm switch of the C phase bridge arm is turned on and the lower bridge arm switch is turned off. The sixth operating state is as follows: the upper bridge arm switch of the A phase bridge arm of the inverter is turned on and the lower bridge arm switch is turned off; both the upper and lower bridge arm switches of the B phase bridge arm are turned off; and the upper bridge arm switch of the C phase bridge arm is turned off and the lower bridge arm switch is turned on.

3. The method for determining the parameters of a motor according to claim 2, characterized in that, After the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter are turned on in a preset manner, the inverter can be in any one of the following working states: the first working state, the second working state, the third working state, the fourth working state, the fifth working state, and the sixth working state. A PWM signal is sent to the inverter to control the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter to conduct in a preset manner, so as to: update the initial PWM carrier cycle by combining the rated current of the motor and the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle, and obtain the current PWM carrier cycle, including: Determine the current threshold of the motor based on its rated current; In the first working state, a PWM signal is sent to the inverter to turn on the inverter. Then the pulse width of the PWM signal is adjusted until the maximum value of the three-phase current of the motor is greater than the current threshold of the motor. At this time, the PWM signal is stopped from being sent to the inverter, and the pulse width of the PWM signal at this time is recorded as the first pulse width of the PWM signal. After a delay until the three-phase current of the motor is 0, a PWM signal is sent to the inverter to turn on the inverter according to the second working state. Then the pulse width of the PWM signal is adjusted until the maximum value of the three-phase current of the motor is greater than the current threshold of the motor. At this time, the PWM signal is stopped from being sent to the inverter, and the pulse width of the PWM signal at this time is recorded as the second pulse width of the PWM signal. In this way, PWM signals are sent to the inverter in the third, fourth, fifth and sixth working states in sequence to turn on the inverter, and the third, fourth, fifth and sixth pulse widths of the PWM signal are obtained in sequence. After a delay until the obtained three-phase current of the motor is 0, the minimum pulse width among the first pulse width, second pulse width, third pulse width, fourth pulse width, fifth pulse width, and sixth pulse width of the PWM signal is determined to update the initial PWM carrier period and obtain the current PWM carrier period.

4. The method for determining the parameters of a motor according to claim 2, characterized in that, After the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter are turned on in a preset manner, the inverter can be in any one of the following working states: the first working state, the second working state, the third working state, the fourth working state, the fifth working state, and the sixth working state. The line current of the motor includes: a first line current, a second line current, a third line current, a fourth line current, a fifth line current, and a sixth line current; A PWM signal is sent to the inverter again, and the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter are controlled to conduct in a preset manner, so as to calculate the line current of the motor based on the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle, including: In the first working state, a PWM signal is sent to the inverter to turn on the inverter. After one current PWM carrier cycle, the PWM signal is stopped from being sent to the inverter, and the line current of the motor is calculated based on the three-phase current of the motor obtained at this time, which is used as the first line current. After a delay of three current PWM carrier cycles, a PWM signal is sent to the inverter to turn on the inverter according to the second working state. After one current PWM carrier cycle, the sending of the PWM signal to the inverter is stopped, and the line current of the motor is calculated based on the three-phase current of the motor obtained at this time, which is used as the second line current. In this way, PWM signals are sent to the inverter in the third, fourth, fifth and sixth working states in sequence to turn on the inverter, and the third line current, the fourth line current, the fifth line current and the sixth line current are obtained in sequence to obtain the line current of the motor.

5. The method for determining the parameters of a motor according to claim 1 or 2, characterized in that, The parameters of the motor include the position angle of the motor, as well as the quadrature-axis inductance and direct-axis inductance of the motor; Based on the line current of the motor, the required parameters of the motor are calculated, including: The line inductance of the motor is calculated based on the line current of the motor. The shaft inductance of the motor is calculated based on the line inductance of the motor; the shaft inductance of the motor includes: the quadrature-axis inductance and the direct-axis inductance of the motor; The position angle of the motor is calculated based on the motor's shaft inductance; and the calculated position angle, quadrature-axis inductance, and direct-axis inductance of the motor are used as the parameters of the motor to be determined.

6. The method for determining the parameters of a motor according to claim 5, characterized in that, The calculation of the required parameters of the motor based on the line current of the motor also includes: The shaft inductance of the motor is calculated based on its line inductance, and the position angle of the motor is calculated based on its shaft inductance, including: Based on the line inductance of the motor, the shaft inductance and the position angle of the motor are calculated using the following formula: Among them, L ab L bc L ca The three line inductances of the motor are, in order, the first line inductance, the second line inductance, and the third line inductance, L. d L is the quadrature-axis inductance of the motor. q Let θ be the direct-axis inductance of the motor. e Let be the position angle of the motor, and k3 be the third calculation coefficient.

7. A parameter determination device for a motor that uses the motor parameter determination method as described in claim 1 to determine motor parameters, characterized in that, The motor has a drive system and three-phase windings; the drive system of the motor has an inverter, the inverter having a three-phase full-bridge inverter bridge composed of a first switch, a second switch, a third switch, a fourth switch, a fifth switch, and a sixth switch; the first switch and the fourth switch are the upper and lower bridge arm switches of the A-phase bridge arm, and are used to supply power to the U-phase winding of the motor's three-phase windings; the third switch and the sixth switch are the upper and lower bridge arm switches of the B-phase bridge arm, and are used to supply power to the V-phase winding of the motor's three-phase windings; the fifth switch and the second switch are the upper and lower bridge arm switches of the C-phase bridge arm, and are used to supply power to the W-phase winding of the motor's three-phase windings; the parameter determination device for the motor includes: The acquisition unit is configured to acquire a preset PWM carrier period as an initial PWM carrier period; acquire the rated current of the motor; and, when the inverter is turned on, acquire the three-phase current of the motor. The control unit is configured to send a PWM signal to the inverter according to the initial PWM carrier cycle when the motor is stationary, and control the upper and lower bridge arms of the A-phase bridge arm, the upper and lower bridge arms of the B-phase bridge arm, and the upper and lower bridge arms of the C-phase bridge arm of the inverter to conduct in a preset manner, so as to update the initial PWM carrier cycle by combining the rated current of the motor and the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle, and obtain the current PWM carrier cycle. The control unit is further configured to send a PWM signal to the inverter again according to the current PWM carrier cycle, and control the upper and lower arms of the A-phase bridge arm, the upper and lower arms of the B-phase bridge arm, and the upper and lower arms of the C-phase bridge arm of the inverter to conduct in a preset manner, so as to calculate the line current of the motor based on the three-phase current of the motor obtained when the inverter is controlled according to the initial PWM carrier cycle; The control unit is also configured to calculate the required parameters of the motor based on the line current of the motor.

8. An electric motor, characterized in that, include: The parameter determination device for a motor as described in claim 7.

9. A storage medium, characterized in that, The storage medium includes a stored program, wherein, when the program is executed, it controls the device containing the storage medium to perform the parameter determination method for the motor according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the method for determining the parameters of the motor as described in any one of claims 1 to 6.

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